Where have all the Feld-Hells gone? No, this is not the title of a nostalgic folk song that I just composed! It is a Frequently Asked Question:
how many were built and how many still exist today? The total production volume
is usually estimated at 14 to 15 thousand units. I do not know exactly where
this number originated, or how valid it is - see discussion further below. This is one of the reasons that I
have started collecting detailed information on surviving Feld-Hell machines. So
far, I have captured information on about 185
complete and partial machines (latest update:
23 April 2020). The information is captured in
this database.

If you own, or have access to, a Feld-Hell machine, please provide me with all information (preferably in the form of clear photos) on the
labels ("Typenschild") of the front and back of the machine's sub-units, as well as stamps and other markings. You can contact me
here.

Fig. 1: Location of the many markings on a Feld-Hell set

The graph below shows the number of Feld-Hell electronic boxes and
motor-generators for the period 1935-1945, based on the information in
my
database. The total number of units is small compared to the estimated total
production volume - about 1%. So, extrapolations to the actual production
volume in each of those years (hence, the shape of the two curves) should be made very carefully.

Fig. 2: Number of electronics boxes and motor-generators in my database for each year

Not surprisingly, the graph suggests
that the production volume surged towards 1940. That may correspond to equipage
of an increasing number of Wehrmacht Signal Corps units for the invasion
of France and the Low Countries. After those invasions, the production effort
the German arms industry was clearly scaled back, even though planning for the
invasion of the Soviet Union ("Unternehmen Barbarossa", Operation
Barbarossa), was already in progress. That invasion started mid-1941. The
hard-fought German defeat at Stalingrad in January of 1943 was a turning point,
and the German retreat started after the Battle of Kursk during the summer of
1943. In parallel, the Tunisia Campaign ended with German surrender in May of
1943. This meant that during 1943, Wehrmacht Signal Corps units had to be
re-formed and re-equipped. This may explain the production surge in that year, as
is evident in the graph above. In Fig. 2 above, the 1935-1938 annual production
volume for motor-generator and amplifier boxes is quite different; however,
their sum over these years is basically identical.

Note that the annual number of electronic boxes and motor-generator serial numbers in my database are not the same. On some of them, I have no information, whereas others are partial machines, or only a motor-generator or amplifier box. However, the total number is
roughly the same. The
Mende company produced a total of 4382 Feld-Hell machines during the years 1941-1943 (ref. 5). Assuming a relatively steady production during the (pre-war) years, Mende would have produced about half of the total, the other half being produced by Siemens-Halske.

Some observations from my data base:

The lowest serial number of an electronics box: 0053 of 1936. The associated motor-generator, also from 1936, has serial number 10053.

highest serial number of an electronics box: 15875 of 1944

highest serial number of a motor-generator: 15640 of 1944

so far, I have captured no electronics boxes that were manufactured in 1937 or 1945 (but this does not necessarily mean that none were built in those years...).

so far, I have captured no motor-generators that were manufactured in 1935, 1937, or 1945.

the 1936 peak production of motor-generators is followed
by two years of (near) zero production.

some motor-generators have different serial numbers on the front and the back (e.g., 5284/1941 and 23877/1941).

sometimes the same serial number is found on an electronics box and a motor-generator, but the year of manufacturing differs by one; in one case, I found 4 years difference (1940 e-box vs. 1936 motor-generator)

with very few exceptions, only the label on the electronics boxes and the motor-generators has a year of manufacture.

several base-units (the module below the motor-generator and keyboard) have a serial number that is much higher than those found on electronics boxes and a motor-generators (e.g., 21898/1940).

Note: one should be careful when making statements about production volume, strictly based on serial numbers! Obviously, for spares provisioning and manufacturing stock, more sub-units where built than complete machines. Serial numbers of military equipment where not always assigned on a consecutive (running) numbering basis ("Durchnummerierung"). They were sometimes assigned in blocks that were not completely used. Also, consecutively manufactured units where sometimes assigned serial numbers from different blocks. This was primarily done to confuse the enemy, when trying to draw conclusions about production volumes based on serial numbers and date of manufacture that was marked on captured units (ref. p. 244. 437 in ref.
6). The two figures below show the blocks of serial numbers of the Feld-Hell amplifier boxes and motor-generators in my database.

Fig. 4: Distribution of the serial numbers of Feld-Hell motor-generators in my database

At the conclusion of the war, a directive was issued to the occupying forces (at least the western
Allies), calling for the capture and destruction of all military equipment and materiel. Also, the public was ordered by the military government to surrender all telecommunications equipment (including carrier pigeons!). Ref. 1, 2. Of course, a search-and-grab was organized to systematically capture and carry off all items and intellectual property
that was of value due to its advanced
"high tech" nature (e.g., "Operation Paperclip"). Ref. 3, 4.

It is impossible to determine how many Feld-Hell machines still exist around the world today, in private collections, museums (on display or in storage), private attics, basements, and garages. Their condition ranges from
"mint and operational" to "barely suitable to be cannibalized for spare parts". I estimate the number of surviving Feld-Hells to be somewhere
between two and three hundred...

Fig. 5: Front & back of a Siemens-Halske equipment tag also used in the Hellschreiber factory